Lisbon , Portugal -LRB- CNN -RRB- -- Calling it a significant step forward for the alliance and European security , President Obama announced Friday that NATO will develop a missile defense system to safeguard most of Europe and the United States .

The agreement , according to the president , followed a year of talks to determine the best ways to coordinate efforts to protect members of the 61-year-old alliance .

The system would be `` strong enough to cover all NATO European territory and populations , as well as the United States , '' Obama told reporters in Lisbon , Portugal .

The missile defense plan `` offers a role for all of our allies in response to the threats of our times , '' the president said . `` It shows our determination to protect our citizens from the threat of ballistic missiles . ''

Obama addressed reporters during the first day of what he promised would be a `` landmark summit '' featuring leaders of NATO 's 28 member countries , as well as Russia . By the time it wraps Saturday , the alliance aimed to produce a set of new initiatives intending to reinvigorate and redirect NATO 20 years after the end of the Cold War .

NATO Secretary-General Anders Fogh Rasmussen announced Friday that heads of state had agreed to a new mission statement , calling it the alliance 's `` road map for the next 10 years . '' Crafting this so-called strategic concept had been a top priority of the meeting , which Rasmussen last month deemed `` one of the most important summits in the history of our alliance . ''

`` This strategic concept reconfirms the commitment by NATO members to defend one another against attack , and that will never change , '' Rasmussen said in Lisbon . `` But it also modernizes the way NATO does defense in the 21st century . ''

The document , prepared from recommendations made by a panel led by former U.S. Secretary of State Madeleine Albright , sought to build upon NATO 's work in Afghanistan to redefine the alliance as a `` global '' actor that would work with regional partners to combat threats outside Europe .

Under the new plan , NATO will bolster its role in counterinsurgency efforts , as well as the stabilization and reconstruction of key countries , according to Rasmussen . The defense alliance will also develop `` a standing capability to train local security forces '' and create a civilian arm to deal with other nations and groups .

Obama added Friday that NATO , under Rasmussen , was also looking at how to deal with threats like improvised explosives and cyber defenses , all serving a commitment that `` an attack on one NATO member is an attack on all . ''

Afghanistan will be front and center on Saturday 's agenda , with NATO members working with others who have committed resources to the nation and its government to `` align our approach , '' according to Obama . He said that includes having Afghan forces transition , between 2011 and 2014 , taking over the security and governance mission in the country and forging a `` long-term partnership '' beyond that .

Russia 's relationship with NATO and the United States is also a chief focus Saturday .

Obama said that starting then , NATO will work with Russia `` to build our cooperation with them in this area ... recognizing that we share many of the same threats . ''

In an exclusive interview with CNN 's Chris Lawrence , Georgian President Mikhail Saakashvili said he hoped that Russia 's deepening partnership with NATO would cause Moscow to take a `` more civilized approach '' in dealing with its neighbors .

Russian troops have occupied Georgian territory since its invasion in 2008 . Saakashvili , whose country 's bid to join NATO has been stalled for several years , said that he hoped the alliance 's involvement would prompt Russia to withdraw its troops from Georgia .

`` Once Russia becomes less paranoid , more cooperative , more self-confident in a nicer way -- because I think lots of things have emerged from their almost paranoid sense of insecurity -- hopefully , the small neighbors of Russia hopefully will feel themselves more safe , '' said Saakashvili , who met with Obama on Friday .

Obama reiterated his belief that the U.S. Congress should pass the New START nuclear control treaty , which the U.S. and Russia agreed on last spring but has not been ratified by either nation 's legislatures . U.S. Senate Republicans have held up a vote on START , citing a heavy workload , in the lame duck session before a new Congress comes in next year , and concerns about the strength of the U.S. nuclear arsenal .

Obama said Friday that NATO leaders had called passage of the treaty -- which , among other things , would restart mutual nuclear inspections and limit the arsenal in the two countries -- critical to European and global security .

`` A failure to ratify -LSB- this treaty -RSB- ... will put at risk the substantial progress that has been made in advancing our nuclear security and our partnership with Russia , '' Obama said .

The search for a new mandate for the entire alliance comes at a time that 16 of the 28 NATO members have announced cuts in defense spending . NATO officials said leaders are expected to agree at the summit on a list of the top 10 spending priorities , including helicopters , transfer aircraft , technology to combat improvised explosive devices and increased medical capabilities .

The outcome of the war in Afghanistan is intrinsically tied to the future of the NATO alliance , a new analysis from the RAND Corporation suggested . The report , published Friday , warns that the U.S. lead in the war could undermine any future willingness to fight together if needed .

`` In an alliance that finds achieving consensus is central , having one partner clearly overshadow all others highlights the real limits of the transatlantic alliance , '' the report said .

The difficulty and length of engagement will weigh on decisions by alliance members to intervene or aid in the future .

`` The scope of NATO 's future roles abroad may be more limited , such as focusing on humanitarian assistance or training , advising , and assisting nations that seek support . While these efforts may entail long-term commitments , they would fall well short of committing combat forces , '' wrote the RAND authors , Andrew Hoehn and Sarah Harting .

The new strategic concept will cite current security challenges facing NATO members in the 21st century , such as terrorism , cyber warfare and piracy .

Rasmussen has encouraged NATO members to be more agile in order to respond to 21st century threats and to continue to invest in military technology despite the global economic downturn . He urged allies to `` cut fat , not muscle '' and pool military spending .

The United States is pushing for a realignment of military spending priorities .

`` We have proposed and hope to have accepted a set of capabilities that the alliance , in a time of dwindling resources , will decide it must fund , '' U.S. Ambassador to NATO Ivo Daalder told reporters earlier this week . `` Those are capabilities that deal with ongoing operations in Afghanistan , but also capabilities to deal with 21st century threats , including beefing up our cyberdefenses and embracing the deployment of missile defenses to protect European territory and populations against the growing threat of ballistic missiles . ''

Obama also will hold a summit with European Union leaders , seeking to reaffirm a partnership with Europe that many feel has gone adrift as the United States expands its partnerships in Asia . Jobs and economic growth are expected to top the agenda at a time of growing tension between U.S. and European countries over the way to fix the global economy .

While the United States has pushed for stimulating economic expansion with more government spending , many European allies are tightening their belts .

The future of some 80,000 U.S. military forces in Europe will also be discussed . European leaders are looking for Obama to keep U.S. troops at their current levels , although the Obama administration has urged Europe to share more of the burden of its own defense .

CNN 's Adam Levine contributed to this report .

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NEW : NATO members agree on a new mission statement for next 10 years

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NEW : Georgian president hopes NATO will spur Russia to be `` more civilized ''

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NATO leaders , among others , are meeting for a two-day summit in Portugual

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One goal for the leaders is to reinvigorate the NATO alliance , 20 years after the Cold War